My name is Kate, and I'm a germaphobe. I won't shake your hand if you look a little peaked, and I'll discreetly move away if you cough on the subway. I'm an expert at elbowing open a swinging door, as well as knuckling my way through an ATM transaction. The arrival of my daughter four years ago seems to have shifted my functional phobia into overdrive. One afternoon, as I sanitized every page of a children's board book from the library, I began to worry that I'd crossed a line.

It was time for professional help. I met with Philip Tierno, Ph.D., the director of clinical microbiology and immunology at the NYU Langone Medical Center. Teirno told me that, "germs are everywhere-but only 1 to 2 percent of the known microbes can do us harm." Plus, most of these germs are beneficial. So how can you protect yourself from the bad guys without sterilizing everything in sight?

It's possible with some smart strategies. Since some 80 percent of all illnesses are passed by human contact, either directly or indirectly, says Tierno, we have the power to avoid the most common routes of germ transfer.

But where are those? Tierno gave me two dozen giant cotton swabs to rub on things I touch daily that he'd analyze at his lab. Here's where the germs really are (and what to do about them):

The results: More than half of my specimens had evidence of fecal contamination. There were Escherichia coli (E. coli) and enterococci, both infection-causing bacteria that were living on the shopping cart and pen at my local grocery store, the sink and door handles in the bathroom of my coffee shop, the buttons of the ATM and copy machine I use, and the playground jungle gym where my daughter plays.

Tierno explained that E. coli from humans is not the same as the animal-produced strain that sickens people but it contains other pathogens, like norovirus, one of the main causes of food poisoning.

The dirty truth: This is proof that most people don't wash their hands after using the bathroom," said Tierno. In fact, more than half of Americans don't spend enough time with the soap, leaving germs on their hands.

Take-home lesson for a clean environment: According to Tierno "Wash your hands often-at least before and after eating and after using the bathroom." To do it properly, wash the tops, palms, and under each nail bed for 20 to 30 seconds (or sing "Happy Birthday" twice). Because germs are attracted to wet surfaces, dry your hands with a paper towel. If you're in a public restroom, use that same towel to turn off the faucet and open the door to avoid recontamination. If you can't get to a sink, alcohol-based sanitizers are your next best line of defense.

Test Area #2: The Kitchen

The results: "The counter was the dirtiest sample of the bunch," Teirno said. The petri dish was overflowing with E. coli, enterococci, enterobacterium (which can make immuno-compromised people sick), klebsiella (which can cause pneumonia and urinary tract infections, among other things), and more.

The dirty truth: A recent study from the University of Arizona shows that the average cutting board contains 200 times more fecal bacteria than a toilet seat does. Fruits and vegetables, in addition to raw meats can be loaded with animal and human debris. By wiping down my counters with a month-old sponge, I may be spreading the bacteria around.

Take-home lesson for a clean environment: "Wash your cutting board with soap and water after every use," advises Tierno, "and use a separate one for different foods. To keep your sponge safe, Tierno recommends microwaving it in a bowl of water on high for at least two minutes each time you use it before and after prepping meals. Tierno uses a solution of one shot glass of bleach to a quart of water. (For a shortcut, use an antibacterial wipe, such as those made by Clorox.) If you want to keep harsh chemicals out of your home, use non-chlorine bleach (3% hydrogen peroxide).

Test Area #3: The Office

The results: Even though my home laptop had a little E. coli on it, he declared it "pretty clean." But a friend's Manhattan office didn't fare as well. Even the elevator button harbored Staphylococcus aureus (S. aureus), a bacteria that can lead to skin infections, and candida (vaginal or rectal yeast), which is harmless-but gross. Once you get to your desk, you're not much better off. A lot of us keep food at our desks, giving microbes a daily feast.

The dirty truth: "Everyone presses elevator buttons, but no one cleans them," says Tierno, who suggests washing up afterward or using a hand sanitizer.

The results: Research published in the Clinical Journal of Sports Medicine found that 63 percent of gym equipment had the cold-causing rhinovirus. At my gym the Arc Trainer handles were teeming with S. aureus.

The dirty truth: Athlete's foot fungus can survive on the surface of mats. And, in a separate analysis, Tierno found that the shower floor was the filthiest place in the gym.

Tierno says germs need specific environments to do harm and the point of knowing what's out there is not to fuel germaphobes like me, but to remind us that exercising caution does keep us healthier.

With that in mind, I'll continue to wash my hands and kitchen regularly and have my daughter do the same. I still have hand sanitizer in my purse, but I don't whip it out all the time. And I no longer wipe down her library books-Tierno tells me paper is a poor germ transmitter anyway.